The present disclosure relates to ultrasound imaging devices, and more particularly, to a method and apparatus for a 1-D array ultrasound probe.
Phased array ultrasonic imaging systems have been used to produce real-time images of internal portions of the human body. Such imaging systems include a multiple channel transmit beamformer and a multiple channel receive beamformer either coupled to a single array of ultrasonic transducers using a transmit/receive switch, or coupled separately to a transmit transducer array and a receive transducer array. The transmit beamformer generates timed electrical pulses and applies them to the individual transducer elements in a predetermined timing sequence. The transducers respond to the electrical pulses and emit corresponding pressure waves, which are phased to form a transmit beam that propagates in a predetermined direction from the transducer array.
As the transmit beam passes through the body, a portion of the acoustic energy is scattered back toward the transducer array from tissue structures having different acoustic characteristics. An array of receive transducers (which may be the same as the transmit array) converts the pressure pulses into the corresponding electrical pulses. Due to different distances, the ultrasonic energy scattered from a tissue structure, arrives back at the individual transducers at different times. Each transducer produces an electrical signal that is amplified and provided to one processing channel of the receive beamformer. The receive beamformer has a plurality of processing channels with compensating delay elements connected to a summing element. The system selects a delay value for each channel to collect echoes scattered from a selected point.
Consequently, when the delayed signals are summed, a strong signal is produced from signals corresponding to the selected point, but signals arriving from other points, corresponding to different times, have different phase relationships and thus destructively interfere. The relative delays of the compensating delay elements control the orientation of the receive beam with respect to the transducer array. By varying the delays during reception of echoes from a given transmit event, the receive beamformer can steer the receive beam to have a desired direction and can dynamically focus over a range of depths.
To collect imaging data, the transmit beamformer directs the transducer array to emit ultrasound beams along multiple transmit scan lines distributed over a desired scan pattern. For each transmit beam, the receive transducer array connected to the receive beamformer synthesizes one or several receive beams having selected orientations. The transmit and receive beams form a round-trip beam (i.e., xe2x80x9ccenter of massxe2x80x9d beam) that is generated over a predetermined angular spacing to create a wedge-shaped acoustic image or is generated over a predetermined linear spacing to create a parallelogram-shaped acoustic image. Arbitrary combinations of the aforementioned patterns can be used to create more complex scanned image shapes, with arbitrary density of acoustic sampling.
A one-dimensional array may have up to several hundred elements. These elements are typically connected to a system with 128 channels of processing electronics. The receive beamformer within these channels uses digital signal processing involving an A/D converter and digital circuitry. This circuitry takes a substantial amount of size and power such that a hand held system cannot be built using this method.
Generally, ultrasound imaging devices are large, expensive ultrasound devices that connect to probes which do not contain integrated high voltage pursers, nor transmit/receive beamforming, and are not very portable.
Accordingly, it would be desirable to provide an ultrasound imaging system architecture that uses a large transducer array for providing two-dimensional images and that is practical in size, cost and complexity.
A phased array ultrasound scanning apparatus includes a one-dimensional (1-D) array of ultrasound transducer elements having transmit and receive elements. The 1-D array is responsive to a transmitter configured to energize the transmit elements for generating a transmit acoustic beam directed into a region of interest. A receive beamformer, operatively connected to the 1-D array, synthesizes receive beams, in response to echoes of the transmit acoustic beam received from the region of interest. The receive beamformer includes analog random access memory (ARAM) delay elements configured to delay signals received from the receive elements and provide the delayed signals on an output of the receive beamformer as a beamformed RF output. The beamformed RF output is suitable for use in forming an image of the region of interest.